A standard central motor-vehicle lock system has a plurality of door latches on the individual doors, hatches, trunk lids, and the like that are each operable by a respective power actuator and also by a manual mechanism. The power actuator can include a hydraulic, pneumatic, or electric motor, and the manual mechanism is almost always a lever linkage.
In a standard system such as described in my U.S. Pat. No. 4,342,209 each door latch has a locking lever displaceable between a pair of end positions corresponding to locked and unlocked conditions of the respective door. This lever is connected on the one side via a rod to the inside unlocking button in the case of a door and on the other side via another rod to the power actuator which is mounted in the door at some distance from the latch. Thus either the knob or the actuator can be operated to lock or unlock the door.
As described in commonly owned U.S. Pat. No. 5,056,343 issued 15 Oct. 1991 the actuator for such a lock system has an electric motor whose output shaft carries a drive pinion that is in continuous mesh with a larger-diameter output gear carried on a threaded spindle in turn carrying a nut. This nut is coupled via a system of deflectable arms to the actuating element. Thus the latch can be moved manually or by the motor between the locked and unlocked position. When moved manually from the locked to the unlocked position, it is necessary for the motor to be operated to move the nut back into the corresponding position before motor-powered operation can resume.